I'm setting up IP Phone Agent on phones an environment with CUCM 6.1 and UCCX 5. The agent and supervisor GUIs work, I'm just trying to make it so that people can log in on their phones. I created the service and subscribed phones to it, but when I try to use the service it times out and says it can't find the URL. There are now ACLs between the phone and the UCCX server and extension mobility, which is also enabled, works. I saw something on one of the sites saying that a "telecaster" user was required. Is this really the case? I only saw it in one location. If this is the case, does the password really have to be "telecaster"? It doesn't meet password complexity requirements for this client.
You should take a look at the CAD Installation Guide for instructions on how to properly configure this. It is documented starting on page 52.
Cisco CAD Installation Guide for CAD 6.6 for Unified CM
Configure a "One Button Login" for IP Phone Agents